deduplicate game states at end of leg

main.nim

@@ -1,4 +1,4 @@
-import math, options, tables, sequtils, sets, sugar
+import math, hashes, options, tables, sequtils, sets
 import combinators
 
 
@@ -7,8 +7,8 @@ type
     cRed, cGreen, cBlue, cYellow, cPurple
 
   Tile = enum
-    tForward = -1,
-    tBackward = 1
+    tBackward = -1,
+    tForward = 1
 
   Square = object
     camels: seq[Color]
@@ -18,17 +18,41 @@ type
 
   ScoreSet = array[Color, int]
 
+  LegResults = tuple[scores: ScoreSet, endStates: HashSet[Board]]
+
   Board = object
     squares: array[1..16, Square]
     camels: array[Color, range[1..16]]
-    leader: Color
+    leader: Option[Color]
     gameOver: bool
 
 
+const allDice = @[cRed, cGreen, cBlue, cYellow, cPurple]
+
+
+proc update(scores: var ScoreSet, toAdd: ScoreSet) =
+  for i, s in toAdd:
+    scores[i] += s
+
+
 proc `[]`[T](b: var Board, idx: T): var Square =
   b.squares[idx]
 
 
+proc hash(b: Board): Hash =
+  var h: Hash = 0
+  # there could be a tile anywhere so we have to check all squares
+  for i, sq in b.squares:
+    if sq.camels.len > 0 or sq.tile.isSome:
+      h = h !& i
+      if sq.tile.isSome:
+        h = h !& int(sq.tile.get) * 10 # so it isn't confused with a camel
+      else:
+        for c in sq.camels:
+          h = h !& int(c)
+  result = !$h
+
+
 proc display(b: Board, start, stop: int) =
   for i in start..stop:
     let sq = b.squares[i]
@@ -40,31 +64,36 @@ proc display(b: Board, start, stop: int) =
   echo ""
 
 
-proc setLeader(b: var Board) =
-  b.leader = b[b.camels.max].camels[^1] # top camel in the last currently-occupied space
-
-
-proc setState[T](b: var Board, state: T) =
-  for (color, dest) in state: # note that `state` is ordered, as this determines stacking
+proc setState(b: var Board; 
+              camels: openArray[tuple[c: Color, p: int]];
+              tiles: openArray[tuple[t: Tile, p: int]]) =
+  for (color, dest) in camels: # note that `camels` is ordered, as this determines stacking
     b[dest].camels.add(color)
     b.camels[color] = dest
-  b.setLeader
+
+  for (tile, dest) in tiles:
+    b[dest].tile = some(tile)
+
+  let leadCamel = b[max(b.camels)].camels[^1] # top camel in the last currently-occupied space
+  b.leader = some(leadCamel)
 
 
 proc advance(b: var Board, die: Die) =
   let
     (color, roll) = die
     startPos = b.camels[color]
-  var prepend = false
   var endPos = startPos + roll
   
   if endPos > 16: # camel has passed the finish line
-    b.leader = color
+    b.leader = some(b[startPos].camels[^1])
     b.gameOver = true
     return
-  if b[endPos].tile.isSome:
-    endPos += int(b[endPos].tile.get)
-    if b[endPos].tile.get == tBackward: prepend = true # if moving backward, we will prepend camel to the seq
+
+  var prepend = false
+  if b[endPos].tile.isSome: # adjust position (and possibly stacking) to account for tile
+    let t = b[endPos].tile.get
+    endPos += int(t)
+    if t == tBackward: prepend = true
 
   for i, c in b[startPos].camels:
     if c == color:
@@ -77,40 +106,50 @@ proc advance(b: var Board, die: Die) =
       b[startPos].camels[i .. ^1] = @[]
       for moved in subStack:
         b.camels[moved] = endPos
-      b.setLeader
+      # if we are stacking on or moving past the previous leader
+      if endPos >= b.camels[b.leader.get]:
+        b.leader = some(b[endPos].camels[^1])
       break # breaking the outer loop here, not the inner - but only conditionally! gah!
 
 
-type CamelPositions = seq[tuple[square: int, camels: seq[Color]]]
-
-proc simulateLeg(b: Board, diceRemaining: seq[Color]): ScoreSet =
+proc simulateLeg(b: Board, diceRemaining: seq[Color]): LegResults =
+  var scores: ScoreSet
   var endStates: HashSet[Board]
   for future in possibleFutures(diceRemaining):
     var prediction = b # make a copy
     for dieRoll in future:
       prediction.advance(dieRoll)
-    inc result[prediction.leader]
+    inc scores[prediction.leader.get]
     # deduplicate results
-    endStates.incl(prediction) # need to add hash implementation for Board
-    #[
-    var positions: CamelPositions
-    for i in prediction.camels.min .. prediction.camels.max:
-      positions.add((i, prediction.squares[i].camels))
-    endStates.incl(positions)
-    ]#
-  echo "Distinct end states: ", endStates.len
+    endStates.incl(prediction)
+  result = (scores, endStates)
+
+
+proc simulateGame(b: Board, diceRemaining: seq[Color]): ScoreSet =
+  # currently just simulates two legs, not a full game
+  var (scores, startStates) = b.simulateLeg(diceRemaining)
+  var endStates: HashSet[Board]
+
+  for s in startStates:
+    let (nextScores, nextStates) = s.simulateLeg(@[cRed, cGreen, cBlue, cYellow, cPurple])
+    scores.update(nextScores)
+    endStates.incl(nextStates)
+    stdout.write("simulated: " & $scores.sum & "\r")
+
+  echo "\nDistinct end states: ", endStates.len
+  result = scores
 
 
 var b: Board
 b.display(1, 5)
 
-b.setState({cGreen: 4, cYellow: 3, cPurple: 4, cBlue: 3, cRed: 2})
+b.setState({cGreen: 4, cYellow: 3, cPurple: 4, cBlue: 3, cRed: 2}, @[])
 b.display(1, 5)
 
 b.advance((cRed, 2))
 b.display(1, 5)
 
-let r = b.simulateLeg(@[cRed, cGreen, cBlue, cYellow, cPurple])
+let r = b.simulateGame(allDice)
 let total = r.sum
 for i, c in r:
   echo Color(i), ": ", (100 * c / total).round(2), "% (", c, " / ", total, ")"